QUALITYWORKS.

Lightweight automobile – the answer lies in the materials!

Hyundai-Kia Motors, inarguably Korea’s top automaker, uses plastics for the front-end module of more than half of their models, including its top-tier sedan brand, Genesis. Front-end modules mount components such as headlights and radiator. Plastics is a surprising material choice for such a critical part like front-end, because it has to perform also during the crash on the front side of a car, thus directly related with safety. LANXESS, the material provider, explains it is possible because the high-performance plastics reinforced with glass fibers can be molded into extremely rigird structures.

Han Sanghoon, Head of the High Performance Materials business units in Korea, said, “LANXESS Durethan® is lighter than metal by as much as 50% with similar level of strength, making it a lightweight alternative for metal. Not only are they corrosion resistant but they can be combined with other materials such as metal or other plastics via hybrid technology, while maintaining the strength comparable to pure metal components.” He also added, “Plastics are estimated to make up approximately 15% of a car nowadays, but the percentage is likely to reach up to 20% in 10 years. Given the continued growth in car production volume around the world, the actual market impact is expected to be larger.”

Why lightweight automobile?

Mini Cooper, the subcompact model, weighed a mere 560kg when it was first launched in 1959. Today, almost 60 years after, it weighs as much as 1,070kg. Size specs did not change much but a wide variety of auxiliary devices for safety and convenience were added such as airbag, ABS, air conditioner and audio, almost doubling the weight. Penetration of electronic vehicles is growing as eco-friendliness and energy efficiency gain importance, and the electric battery, which is often dubbed as the solution for energy and emission saving, weighs often more than 250kg.

When the weight of an internal combustion engine car increases by 100kg, it is typically estimated that CO2 emission increases by about 11g per 1km, fuel consumption by 0.5L per 100km. Consequently, lightweight automobile is a significant challenge for today’s automotive industry.

As fuel consumption is cited as the culprit of global warming, countries around the world are adopting ever stricter regulations on energy and carbon emission. The Korean government demands to raise average mileage for a passenger car from 17km/L in 2015 to 24.3km/L in 2020. Korea’s mileage standard is one of the highest in the world. During the same period, CO2 emission requirements will be tightened from 140g/km to 97g/km.

Lightweight automobile enabled by Lanxess solution

There are three major methods that can realize manufacturing of lightweight automobile: 1) structure design change, 2) new technology and 3) new materials. Most realistically effective option among these is the use of lightweight materials, especially “high tech plastics that can replace metal”. According to the research by McKinsey, a business management consulting firm, replacement of steel parts with new materials such as high-tech plastics or light metals in a car can result in weight loss of 420kg to 490kg depending on the mix of materials.

Durethan® is one of the most representative substitutes for metal. The areas to which lightweight designs are applicable include body, chassis, drivetrain and interior. Polyamide-based Durethan can be applied to all of them. Highly heat-resistant, durable and strong, it weighs only 1/6 of steel. Furthermore, it has the perfect properties as a material for curvy body parts thanks to its high formability comparable to thin metal board. Most importantly, it is cited as a realistic alternative for lightweight automobile despite other recent candidates like composite materials such as carbon-fiber-reinforced plastic because it can replace metal for a similar cost.

Major applications are generally lightweight, high-strength parts such as front-ends, roof frame, engine oil pan, airbag housing, and brake pedal that used to be made with metal. As we enter the era of EV, the range of applications is ever increasing including battery housing, battery cell frame, high voltage connectors, and electronic charger, etc.

Hybrid technology is the mainstream for the materials as well

Special ‘hybrid technology’ combining plastic and metal or different types of plastic materials can deliver a clear weight reduction effect. Han said, “Use of plastic-metal hybrid materials leads to parts weight reduction by as much as 50% compared to steel. This patented technology was successfully applied to front ends of more than 70 car models by OEMs including Hyundai-Kia, BMW and Audi.”

“Recently, we receive an increasing number of inquiries from the automakers if high-tech plastics or hybrid technology is applicable to the components that are traditionally produced with metal such as engine oil pan and sheet structures,” Han explained.

Also gaining popularity is specialty materials with enhanced performance using continuous glass fibers. These thermoplastic composites e.g. applicable to under-body protection, seat structures, airbag housings, as it offers very high strength and toughness, yet it is also effectively processable that it is already applied in automotive series production. This new material generation of LANXESS is called TEPEX.